A367714 G.f. A(x) satisfies A(x) = 1 / ((1 - x) * (1 - x * (1 + x + x^2) * A(x^3))).

1, 2, 4, 8, 17, 36, 76, 162, 345, 734, 1564, 3332, 7097, 15121, 32216, 68634, 146228, 311544, 663748, 1414136, 3012859, 6418971, 13675802, 29136686, 62076510, 132255753, 281774605, 600328670, 1279017082, 2724981797, 5805650101, 12369100408, 26352715431

Offset

0,2

Links

Table of n, a(n) for n=0..32.

Formula

a(n) = 1 + Sum_{k=0..n-1} a(floor(k/3)) * a(n-1-k).

Prog

(PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=1+sum(j=0, i-1, v[j\3+1]*v[i-j])); v;

Crossrefs

Cf. A367713, A367715.

Cf. A367656, A367691.

Sequence in context: A008999 A052903 A308745 * A226729 A063457 A262735

Adjacent sequences: A367711 A367712 A367713 * A367715 A367716 A367717

Keyword

nonn

Author

Seiichi Manyama, Nov 28 2023

Status

approved